Novel co initiator systems

ABSTRACT

THE COMBINATION OF TETIARY ALKYL PERESTES OF TERITARY HYDROPEROXIDES AND EITHER ORGANIC AZO COMPOUNDS CONTAINING THE MONOVALENT -CN RADICAL OR DIACYL PEROXIDES USEFUL AS POLYMERIZATION INITIATORS. THESE CON-INITIATOR SYSTEMS ARE PARTICULARLY EFFICIENT IN THE POLYMERIZATION OF CERTAIN VINYL MONOMERS SUCH AS VINYL CHLORIDE.

"United States Patent "ice 3,763,128 NOVEL CO-INITIATOR SYSTEMS Roger N.Lewis, Pinole, and Ronald L. Friedman, San

Rafael, Calif., assignors to Argus Chemical Corporation, Brooklyn, N.Y.

No Drawing. Original application Apr. 8, 1970, Ser. No. 26,768, nowPatent No. 3,687,867. Divided and this application Apr. 19, 1972, Ser.No. 245,285

Int. Cl. C08f 3/ 04, 3/30, 3/68 US. Cl. 260-891 1 Claim ABSTRACT OF THEDISCLOSURE The combination of tertiary alkyl peresters of tertiaryhydroperoxides and either organic azo compounds containing themonovalent -CN radical or diacyl peroxides useful as polymerizationinitiators. These co-initiator systems are particularly efiicient in thepolymerization of certain vinyl monomers such as vinyl chloride.

This is a division of application, Ser. No. 26,768, filed Apr. 8, 1970,now US. Pat. No. 3,687,867.

This invention relates to organic peroxide-containing polymerizationinitiators. More particularly, it relates to the combination of t-alkylperesters of t-hydroperoxides with nitrile-containing azo compounds orcertain aliphatic diacyl compounds and to their use in thepolymerization of monomers such as vinyl chloride.

US. Pat. 3,420,807 describes the polymerization of vinyl monomersthrough the use of a co-initiator composition of certain tertiary alkylperesters and the usual diacyl peroxides such as lauroyl peroxide. Thepresent invention is directed to an improved co-initiator system usefulfor bulk, solution and suspension polymerization and copolymerization ofall the common vinyl monomers including styrene, ethylene, vinylchloride, vinyl acetate, vinyliclene chloride, methyl methacrylate,methyl acrylate and the like. It has been found that the co-initiatorsysterns of this invention provide yields of polymer product, undercomparable conditions of time and temperature, that are substantiallyhigher than with corresponding quantities of prior art co-initiators.

In accordance with the present invention the new coinitiator systems areselected from certain peresters in combination with certain aliphaticdiacyl peroxides or nitrile-containing azo compounds.

PERESTERS Peresters found to be suitable for this invention have thegeneral formula:

I BALE wherein R and R are alkyl, phenyl, or participate in a cycloalkylgroup where shown in broken lines, R R and R are alkyl, and R isselected from the group consisting of alkyl, alkynyl, phenyl,cyclohexyl, and

3,763,128 Patented Oct. 2, 1973 in which I, m, n, o, and p are integersfrom 0-5 provided the sum of l, m, n, o, and p is at least 1, and R R RR and R are each the same as R R R R and R respectively. Particularlydesirable results are ob tained when the co-initiator is a diacylperoxide, and more than one of R R and R of the perester contains 2 ormore carbon atoms, as hereinafter defined.

A preferred group of peresters is obtained where R is an alkyl,cyclohexyl, phenyl, or alkynyl group so that a monoperester is provided.A typical example within this category is the case where R, R and R areall methyl groups. Such peresters are derived by the esterification oftertiary butyl hydroperoxide in accordance with the following generalreaction:

The same reaction is involved where R is an alkynyl, phenyl, orcyclohexyl group. Such a perester would be obtained for example wherethe following hydroperoxide is used instead of the tertiary butylhydroperoxide shown:

CH: CHEG-C-O OH Equally useful hydroperoxides include: (1)l-cyclohexyl-l-hydroperoxy ethyne-l (2) 3-methyl-3-hydroperoxy butyne-l(3) 3-methyl-3-hydroperoxy pentyne-l (4) 3,5-dimethyl-3-hydroperoxyhexyne-l (5) 3-phenyl-3-hydroperoxy butyne-l (6) 3-phenyl-3-hydroperoxypropyne-l (7) 5-methyl-3-ethyl-3-hydroperoxy heptyne-l (8)3-rnethyl-3-hydroperoxy decyne-l (9)3,6-dimethyl-3-hydroperoxy-heptyne-1 (10) 3,5-dimethyl-3-hydroperoxyhexyne-l (11) 3,4-dimethyl-3-hydroperoxy pentyne-l 12)3-methyl-3-hydroperoxy nonyne-l All of the above may be used assaturated hydroperoxides if the acetylenic site is hydrogenated in theusual fashion. The foregoing examples are typical of the possiblecyclohexyl groups which may occur at R as Well as R; and R In general,any alkyl, alkynyl, phenyl, or cyclohexyl group desired is contemplatedfor R, R R in which any rings present may contain alkyl substituents. Inaddition, all of these groups may contain other noninterferingsubstituents such as halogen atoms as desired. For practical purposesthe reactants will generally be selected so that the total perestermolecule obtained contains not more than about 50 carbon atoms so thatthe active oxygen content of the composition will not be too low forcommercial purposes.

Instead of a mouohydroperoxide, dihydroperoxides are contemplatedwhereby a diperester is obtained as the end product. In this case R inthe above general formula is the group:

Typical dihydroperoxides which can be used are:

(1) 2,5-dimethyl-2,S-dihydroperoxy hexyne-3 (2)2,7-dimethyl-2,7-dihydroperoxy octyne-4 (3)3,4,7,8-tetramethyl-4,7-dihydroperoxy decyne- (4)4,7-dimethyl-4,7-dihydroperoxy decyne-S (5)3,6-diethyl-3,6-dihydroperoxy octyne-4 ('6)3,4-dimethyl-3,4-dihydroperoxy pentyne-l Where a dihydroperoxide is usedas. a starting reactant in the esterification reaction given previously,twice the amount of acid halide is used for esterifying the twoavailable sites. A preferred saturated dihydroperoxide for use in thisinvention is 2,5-dimethyl-2,S-dihydroperoxyhexane. Additional saturateddihydroperoxides useful in this esterification reaction for preparingthe present compounds are described in the preparation of disperestersin US. Pat. 3,264,274.

Additional useful acetylenically unsaturated dihydroperoxides useful inpreparing the present peresters are more fully described in connectionwith the peresters of co-pending patent application, Ser. No. 531,352filed Mar. 3, 1966, and now abandoned. A number of patents describe theuse of dihydroperoxides having more than one acetylenic site. Thepreparation of the foregoing peresters is described in co-pending patentapplication, Ser. No. 725,931, filed May 1, 1968, and now Pat. No.3,624,123.

NITRILE-CONTAINING AZO COMPOUNDS Intended to be included in this groupof co-initiators with the peresters are organic azo compounds containinga monovalent CN radical. More particularly, those aliphatic compoundsfound to be useful include nitrile-containing azo free radicalgenerators having the formula wherein R is a branched or straight chainhydrocarbon radical of up to 20 carbons and preferably up to 10 carbons.It is contemplated that R will include non-interfering substituents. Thepreparation of such suitable compounds is disclosed in US. Pat.2,471,959 and includes a,a-azobisisobutyronitrile anda,a'-azobis-2,4-dimethyl valeronitrile.

DIACYL PEROXIDES Broadly, useful diacyl peroxides, well known to thoseskilled in this art, are defined by the following structural formula:

wherein p is an integer of from 1 to 2, R and R are aliphatichydrocarbons of about 7 to 13 carbon atoms, either straight chain orbranched, with the proviso that when R, R and R are methyl and two ormore of R R and R are methyl R and R are hydrocarbons of 7-9 carbonatoms. Although it is desirable that R; and R be unsubstituted,non-hydrocarbon substituents may be included provided they produce noundesirable side effects. Preferred examples of diacyl compounds to beutiilzed in the co-catalyst system of this invention include lauroylperoxide, 3,5,5-trimethylhexanoyl peroxide, pelargonoyl peroxide,myristoyl peroxide and the like. The preparation of the various diacylperoxides included herein as co-initiators is well known to thoseskilled in this art.

Catalyst concentrations, ratios and reaction temperatures can be variedwidely, as they are dictated primarily by commercial equipmentlimitations such as heat exchange capacity or economics. "Preferablyeach component in the co-initiator is present in 'a similar amount offrom 0.01% to 0.50%. Reaction temperatures will vary from 35-70 C. with-65 C. being conventional for most commercial systems.

To further illustrate the process of this invention, the followingexamples are provided. It should be understood that the details thereofare not to be regarded as limitations as they may be varied as will beunderstood by one skilled in this art.

Example I The co-initiators of this invention are most advantageouslyused for the polymerization of styrene, vinyl chloride, vinyl acetate,and ethylene. Typical of the beneficial results obtained are illustratedby the polymerization of vinyl chloride. The peroxides listed in Table Ibelow were prepared by the methods described in co-pending application,Ser. No. 725,931, supra, while the diacyl peroxides and thenitrile-containing compounds were commercially available.

The polymerization procedure used is as follows: Into a 6 /2 fluid ounceCoke bottle, containing 94.0 g. of frozen dispersing solution, wereadded the appropriate amount of peroxide and 50.0 g. of vinyl chloridemonomer. The Coke bottle was capped, the contents almost melted, andthen the bottle is placed in a rotating constant temperature bath at50il C. After the bottle was cooled, and the excess monomer vented, thePVC was filtered, washed, and dried at 40-50 C. for 1216 hours. Thepercent yield of polyvinyl chloride polymer was monitored with re spectto time. The results are shown in Table I.

TABLE I Coke bottle polymerizations at 50 C. 1 C. using vinyl chloridemonomer Percent PVC conversion Conc., 2 4 6 8 10 12 Catalyst percenthrs. hrs. hrs. hrs. hrs. hrs.

1 Lauroyl peroxide 0.50 7 21 38 59 86 93 2 t-Butyl perplvalate 0.05 6 1628 43 60 76 3..-. t-Butyl perneodecanoate 0.053 13 31 55 74 83 86 4g,i'-%z l bis-2,4-d1ingethy1valeronitrile 0.0g 10 24 40 58 75 88 5.... uy perpivaa e..- 0.0

gfiiauripyil peroxige 0. 15 5 14 27 41 54 71 6 u y perneo ecanoa 0.03

Fguroyal peroxige .f- 006;? 10 24 54 67 79 7 uty perneo ecanoa egthguroyil peroxige E- 1O 24 37 52 67 80 8 uty perneo ecanoa e .0

Laurtpyil peroxige g g 11 25 41 5e 71 84 9 t-Bu y perneo ecanoa .0

itPeplartgtinoyl pefioxidenn 0.15 i 10 25 46 60 80 92 10 u y perneoccanoate 0.03 11 iMgthtyllhexanoy peroxige 00652 i 10 30 48 69 85 91 tuy perneo eeanoa e {a,a-Az0bis2,4-dimethy1valeronitrile 0. 025 i 12 27 4357 69 79 It will be seen from Table I that a corresponding quantity ofvinyl chloride monomer conversion is accomplished with 0.50% lauroylperoxide and as little as 0.03 t-butyl perneodecanoate and 0.20% lauroylperoxide. Furthermore, the prior art co-catalyst system composed oft-butyl perpivalate and lauroyl peroxide, in similar quantities,produces significantly less conversion.

Example H A further polymerization was conducted in a one liter,stainless steel autoclave using the following procedure: The autoclavewas charged with a 525 gram suspension solution. The autoclave wassealed and the agitator turned on. Next, 175 grams of vinyl chloridemonomer were injected into the autoclave using nitrogen pressure. Thetemperature was raised to 57 C. Thereafter, a catalyst solution(containing 0.025% tbutyl perneodecanoate and 0.125% lauroyl peroxide)was prepared and injected into the autoclave using nitrogen pressure.After eight hours at 57 C. a sufficient pressure decrease occurred inthe autoclave, indicating high conversion of the monomer to polymer. Theautoclave was vented and the polyvinyl chloride washed and dried to aconstant weight. The percent polyvinyl chloride conversion was found tobe 90%.

Although the foregoing invention has been described in some detail byway of illustration and example for purposes of clarity ofunderstanding, it is understood that certain changes and modificationsmay be practiced within the spirit of the invention as limited only bythe scope of the appended claim.

What is claimed is:

1. In the polymerization of a monomer mass containing a monomer selectedfrom the group consisting of styrene, vinyl chloride, vinyl acetate,vinylidene chloride, methyl methacrylate, methyl acrylate, and ethylene,the improvement comprising initiating the polymerization of said monomermass with a catalytic amount of an organic peroxide co-initiatorconsisting essentially of similar amounts of a perester of the formula:

Br l -Rs R4 in which I, m, n, o, and p are integers from 0-5 providedthe sum of l, m, n, 0, and p is at least 1, and R R R R and R are eachthe same as R R R R and R respectively; and an aliphatic diacyl peroxideof the formula wherein R7 and R are hydrocarbon radicals of 7-13 carbonsand p is an integer of 1 to 2, with the proviso that when R, R and R aremethyl and 2 or more of R R and R are methyl, R and R are hydrocarbonradicals containing 7-9 carbon atoms.

References Cited UNITED STATES PATENTS 3,446,831 5/1969 Mageli et al26085.5 F

HARRY WONG, JR., Primary Examiner US. Cl. X.R.

252426; 260-895 A, 91.7, 92.8 R, 93.5 S, 94.9 R, DIG. 28

